Superheater with temperature control



Dec. 2%, @3 3. D. s. CARTER 1,941,246

SUPERHEATER WITH TEMPERATURE CONTROL Filed July 15, 1932 INVENTOR. ID ouj als S- 'MT r A TTORNEY mally at a high rate of radiant heat absorption Patented Dec. 26, 1933 UNITED STATES I 1,941,24 g U g V SUPERHEATER .VWITH: TEMPERATURE i CONTROL r Douglas S. Carter, Scarsdale, N. .Y., 'assignor to 1 5';

' I The superheater Company, New York,

"Ap i n Ju y 13,1932." SerialNo. 22,18 7

' 6 Claims. 140191 2 7 My invention relates to superheater-"boilers and aims to provide an arrangement wherein the superheater normally absorbs heat at a high rate per unit area, but is protected from-overheating when conditions vary fromthe average. An object. of my invention also is to provide a comparatively cheap arrangement of "boiler and superheater adapted to deliver steam of 'a uniformly high temperature. a

The novel features of myinvention are pointed out in the appended claims. The-invention itself, however, as wellvas its objects and advantages, will best be understood fromthe following detail description, taken in connection-with the accompanying drawing, of a superheater boiler arrangement inaccordance-with my'invention selected by way of example froma. number of possible embodiments thereof. In the drawing, the figure is a vertical sectional elevation through a superheater boiler. v I

It is possible to arrange the superheater for a boiler so that the superheater may receive alarge amountof radiant heat per. unit of surface. Under such conditions, however, there is danger of burning the elements of the superheater when conditions vary. to any {considerable percentage from the average. Furthermore, it is often desired to maintain the temperature of "the steam at the outlet of the superheater of a boiler'close to a given point. Operation at a high rate of radiant heat absorption over most of its surface has usually rendered it more difiicult to prevent wide variation of steam temperature. In accordance with my invention, I arrange the superheater elements so that they will operate norper unit area, but I protect them from overheating and also regulate the temperature of the steam at the outlet of the superheater by passing varying amounts of air in contact'with elements of the superheater when the conditions under which the superheater isoperated depart from the normal. r

In the preferred embodiment of my invention, illustrated in the drawing, the superheater receives its heat largely by radiation so that the the desired degree of superheat is attained at the outlet of the superheater at average full load. At times of average full load, a considerable amount of air is supplied to the furnace but the superheater is in no danger of overheating on account of the cooling due to the large amount of steam. As the .load' dropsoff-Iemplo'y some of the air which is introduced into the furnace tocoolthe superheater.

*In' the arrangementillustrated, boiler 0 is of ,a well knowntypehaving a-furnace chamber 12 therebelow. R'A burneropening l4 isshown in mediate the pier 20 and the rear wall 18. As

header 26 and lie substantially-horizontally' so that flame from a burner in aperture 14iwill pass above them and they will receive heat somewhat ,by direct radiation from such a flame and also by radiation from therear: wall 18;. The natural draft in chamber 12 being upwardmost-of the gases from burner .14 are drawn.away from'the planeof the elements 22. so that such elements receive very little heat by convectiom-z-However,

they are sufficiently close to the flame and to wall 18 so that they receive a large amount of heat per unit area by radiation and can deliver steam of a comparatively high temperature in shown; the :elements 22 are connectedbetween a saturated header-24 andsuperheated'steam proportion to'the surface of the superheater compared to the majority of superheaters.

' Air for combustion of fuel introduced through aperture 14 is supplied in part through the burner aperture itself, but a large amount of secondary air is required for insuring flame stability and complete combustion in furnace 12 and the majority of such secondary air is introduced in the arrangement shown through a duct 30' below the pier 20. Air entering through the duct 30 may rise and pass upwardly 'on either side of pier 20 depending upon the position of a damper 32 pivoted on an axis close to the lower-edge of pier 20. Air passing to the left of pier 20 as shown in the figure rises through a distributing grate 20 the damper 32 is positioned as shown in dotted lines in the figure The damper'32 occupies such dotted line position so. long as the temperature of steam in the superheated steam header 26 is not above the desired temperature. Means, however, are provided so that damper 32 is automatically swung away from the dotted line po- 34= immediately beneath the flame from burner aperture 14. In order to permit the entire stream of air fromduct 30 to pass to the left of pier 20 and opening the passage to the right of such 'pier so that more or less of the air from duct 30 is diverted beneath the elements 22 and rises therethrough so that it not only cools elements 22 by direct contact but also reduces the heat supply to such elements by lifting. the name "farther away therefrom and also cooling the wall 18. The means illustrated for swinging damper 32 in the manner just described-comprisesa ther- V mostat 86 arranged .to control servo-motor 38 having a piston (not shown) therein, but thefpiston rod of which carries a rack "40 engaging a pinion on the shaft 42 of the damper 32 so that the damper is swung from 'right to left in the arrangement shown in Fig. 1 whenevericonditions require that the temperature of steam in header :26 be prevented .fromrrisingfurther. 'It clear :from the drawing that when desired the'entire :fiowof airlfrom thed'uct30 maybeshi'ftedfrom the left side of pier 20 tothe right thereof so :as to coolntheelements 22rand increase the distance-of the'flame therefrom. r I

The n superheaterirhaving :the elements -22 being Of the :radiant type, it hasaa characteristic temperatur'e-curverising with decrease of load. The elements 22 'therefore are apt 1 to :become everheatedaat low floads. It :isz-atlow loads therefore that secondary air will be diverted :over -:or .through the superheater;for'.protective uses as I above described.

Ifidesired, 'moreover, I may :control the fuel supplied to 'the :burner by the thermostat -36 as delivery'of the :secondary air. Such fuel control is not shown, however, asittforms nolpart zof-myxinvention.

In the arrangement shown, ;I :havezprovi'ded an openin'g 46' in the :front wall' 16 *to supply a :certainzamount 1 of secondary. flair 'S-to ichamb'er 12 through grating 34 when the idam'per'l32iiszin its extreme left hand position. :ILido not limitlmy- .seli =to this, "however.

rises-above atgiven point.

What I claim isi I 1. The combination with a boiler and a superheater therefor, of a source of heat common to both said boiler and superheater, means to supply a branched stream of air to said source for supporting combustion, said superheater lying in one branch of said stream, and means for causing the proportion of air from saidstream passing over said superheater to increase as the temperature of steam from the superheater rises .above a given point.

"2. The combination with a boiler and a superheater therefor, of a burner for said boiler arranged to discharge above said superheater to heatit largely by radiation, means for passing a stream of air to the flame from said burner at a point between the burner and. said superheater,

and means to divert a portion of said stream thru such superheater from below upward when the temperature of steam from the superheater 3. The combination assetforth in claim 2-and in which the superheatenelements lie substantially horizontal.

4. ,The method or reguiatingthe temperature '5. The m'ethodasset forthinclaim andzin which :the air :for cooling-the superheater acts also to move the flame ifarther therefrom. :well as the :damperlcfor controllingthepoint of heater comprising burning fuel t01form5a fia'metin radiating relation to the superheater, supplying a stream .of'secondary air' to said flamezand :taking off air from said" stream and :passing :such

air'ins such relationato :said superheater as itoicool it when I the. steam :fiow therethrough is belowla .agiv'en .point.

=DOUGLAS :S. CARTER.

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